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Abstract

Background; Cardiac resynchronization therapy (CRT) improves the clinical status of patients with congestive heart failure, but there is some evidence that left ventricular (LV) pacing may have proarrhythmic potential. Previous investigation reported that LV epicardial pacing results in an increase of transmural dispersion of repolarization, which may be associated with prolongation of Tpeak to Tend interval (Tp-e). However, little is known about time-dependent change of ventricular repolarization in patients with CRT.

Methods; The study group consisted of 55 patients with CRT (66 ± 12 years old, 41 males, 44 ischemic and 11 non-ischemic cardiomyopathy, NHYA class 3.1 ± 0.6, QRS duration 171 ± 33 ms and EF 25.9 ± 9.8 %). Twelve-leads ECG were digitally-recorded and Tp-e was measured at baseline and 1 week, 1 month, 3 months, 6 months and 12 months after CRT device implantation. We investigated the time-dependent changes of Tp-e and the relationship between Tp-e and ventricular arrhythmia (VA) during 12 months of follow-up, and compared those in responder group with those in non-responder group of CRT.

Result; 5 of 12 VA episodes (42%) occurred within one month after the implantation. Tp-e reduced significantly at 6 and 12 months after the implantation compared with baseline (125 ± 18 ms at baseline vs. 115 ± 27 ms at 6months (P<0.05), 113 ± 24 ms at 12 months (P<0.05)). Tp-e in responder group was lower compared with that in non-responder group during the initial 12months (P=0.09). Kaplan-Meier event-free survival analysis demonstrated that the responder group had a significantly lower rate of appropriate ICD therapy (log-rank test, P=0.005).

Conclusion; The prolonged transmural dispersion of repolarization and the proarrhythmic effect occurred within one month after CRT device implantation but reduced over time, especially in CRT responder.